// Fuzzy Hashing by Jesse Kornblum
// Copyright (C) 2012 Kyrus
// Copyright (C) 2008 ManTech International Corporation
//
// $Id: find-file-size.c 144 2012-04-24 14:59:33Z jessekornblum $ 
//

#include "main.h"

// Prototypes
off_t find_file_size(FILE *f);
off_t find_dev_size(int fd, int blk_size);


#ifndef _WIN32

// Return the size, in bytes of an open file stream. On error, return 0 
#if defined (__LINUX__)


off_t find_file_size(FILE *f) 
{
  off_t num_sectors = 0, sector_size = 0;
  int fd = fileno(f);
  struct stat sb;

  if (fstat(fd,&sb))
    return 0;

  if (S_ISREG(sb.st_mode) || S_ISDIR(sb.st_mode))
    return sb.st_size;

#ifdef HAVE_SYS_IOCTL_H
#ifdef HAVE_SYS_MOUNT_H
  if (S_ISCHR(sb.st_mode) || S_ISBLK(sb.st_mode))
  {
#if defined(_IO) && defined(BLKGETSIZE)
    if (ioctl(fd, BLKGETSIZE, &num_sectors))
    {
      return 0;
    }
#else
    // If we can't run the ioctl call, we can't do anything here
    return 0;
#endif // ifdefined _IO && BLKGETSIZE


#if defined(_IO) && defined(BLKSSZGET)
    if (ioctl(fd, BLKSSZGET, &sector_size))
    {
      return 0;
    }
    if (0 == sector_size)
      sector_size = 512;
#else
    sector_size = 512;
#endif  // ifdef _IO && BLKSSZGET

    return (num_sectors * sector_size);
  }
#endif // #ifdef HAVE_SYS_MOUNT_H
#endif // #ifdef HAVE_SYS_IOCTL_H

  return 0;
}  

#elif defined (__APPLE__)

off_t find_file_size(FILE *f) {
  struct stat info;
  off_t total = 0;
  off_t original = ftello(f);
  int fd = fileno(f);
  uint32_t blocksize = 0;
  uint64_t blockcount = 0;

  // I'd prefer not to use fstat as it will follow symbolic links. We don't
  // follow symbolic links. That being said, all symbolic links *should*
  // have been caught before we got here. 

  if (fstat(fd, &info))
  {
    return 0;
  }

#ifdef HAVE_SYS_IOCTL_H
  // Block devices, like /dev/hda, don't return a normal filesize.
  // If we are working with a block device, we have to ask the operating
  // system to tell us the true size of the device. 
  //
  // This isn't the recommended way to do check for block devices, 
  // but using S_ISBLK(info.stmode) wasn't working. 
  if (info.st_mode & S_IFBLK)
  {    
    // Get the block size 
    if (ioctl(fd, DKIOCGETBLOCKSIZE,&blocksize) < 0) 
    {
      return 0;
    } 
    
    // Get the number of blocks
    if (ioctl(fd, DKIOCGETBLOCKCOUNT, &blockcount) < 0) 
    {
    }

    total = blocksize * blockcount;
  }
#endif     // ifdef HAVE_IOCTL_H

  else 
  {
    if ((fseeko(f,0,SEEK_END)))
      return 0;
    total = ftello(f);
    if ((fseeko(f,original,SEEK_SET)))
      return 0;
  }

  return (total - original);
}


#else   // ifdef __APPLE__

// This is code for general UNIX systems 
// (e.g. NetBSD, FreeBSD, OpenBSD, etc) 

static off_t
midpoint (off_t a, off_t b, long blksize)
{
  off_t aprime = a / blksize;
  off_t bprime = b / blksize;
  off_t c, cprime;

  cprime = (bprime - aprime) / 2 + aprime;
  c = cprime * blksize;

  return c;
}



off_t find_dev_size(int fd, int blk_size)
{

  off_t curr = 0, amount = 0;
  void *buf;
  
  if (blk_size == 0)
    return 0;
  
  buf = malloc(blk_size);
  
  for (;;) {
    ssize_t nread;
    
    lseek(fd, curr, SEEK_SET);
    nread = read(fd, buf, blk_size);
    if (nread < blk_size) 
    {
      if (nread <= 0) 
	{
	  if (curr == amount) 
	  {
	    free(buf);
	    lseek(fd, 0, SEEK_SET);
	    return amount;
	  }
	  curr = midpoint(amount, curr, blk_size);
	}
      else 
	{ // 0 < nread < blk_size 
	  free(buf);
	  lseek(fd, 0, SEEK_SET);
	  return amount + nread;
	}
    } 
    else 
    {
      amount = curr + blk_size;
      curr = amount * 2;
    }
  }

  free(buf);
  lseek(fd, 0, SEEK_SET);
  return amount;
}


off_t find_file_size(FILE *f) 
{
  int fd = fileno(f);
  struct stat sb;
  
  if (fstat(fd,&sb))
    return 0;

  if (S_ISREG(sb.st_mode) || S_ISDIR(sb.st_mode))
    return sb.st_size;
  else if (S_ISCHR(sb.st_mode) || S_ISBLK(sb.st_mode))
    return find_dev_size(fd,sb.st_blksize);

  return 0;
}  

#endif // ifdef __LINUX__
#endif // ifndef _WIN32

#if defined(_WIN32)
off_t find_file_size(FILE *f) 
{
  off_t total = 0, original = ftello(f);
  
  // Windows does not support running fstat on block devices,
  // so there's no point in mucking about with them. 

  if ((fseeko(f,0,SEEK_END)))
    return 0;

  total = ftello(f);
  if ((fseeko(f,original,SEEK_SET)))
    return 0;
  
  return total;
}
#endif // ifdef _WIN32